Various systems have been designed to allow automatic (driverless) operation of rapid transit vehicles in mainline revenue service (i.e., passenger carrying operations) using either fixed block or moving block designs.
In a fixed block design the guideway is divided into segments called blocks. Such a design can be appreciated from U.S. Pat. No. 4,166,599 (Auer, Jr. et al.), which issued on Sep. 4, 1979, and which is incorporated herein by reference.
In the system briefly described in U.S. Pat. No. 4,166,599, block boundaries are identified by short vertical strokes through the horizontal line identifying the guideway. An apparatus is arranged in each block, for detecting the presence of a vehicle in that block. This wayside apparatus may be coupled to wayside apparatus of one or more adjacent upstream blocks for the purpose of informing vehicles in such upstream blocks of the presence of a vehicle in a downstream block. In one specific application, for example, the block directly upstream of an occupied block is provided with the signal requiring an emergency stop. The next adjacent upstream block is provided with a signal requiring a stop, the next adjacent upstream block is provided with a signal calling for a low speed, and so on. In effect, an information communication arrangement is combined with distributed wayside data processing or computing. In such a system, the vehicle headway, i.e., the distance between moving vehicles, is at least one block long, and may, in normal practice, be two or more blocks long. Fixed blocks have the disadvantage of not providing maximum performance and cannot be easily overlaid on existing track circuits. They do, however, have the advantage of a distributed architecture.
In the moving block design each vehicle that is being controlled, transmits its location to a controlling authority, usually on a periodic basis. Thus, the controlling authority has available to it information as to the location and, perhaps speed, of all the vehicles being controlled. Under these circumstances, the controlling authority then provides signals to the vehicles, based upon downstream traffic conditions, allowing the vehicles to proceed at safe speeds, or on the other hand, requiting the vehicles to stop. See U.S. Pat. No. 4,711,418 (Auer, Jr. et al.), which issued on Dec. 8, 1987 and which is incorporated herein by reference. Moving block systems improve performance but are highly centralized leaving availability and start-up problems.
A third method for automatic (driverless) operation is also set forth in U.S. Pat. No. 4,166,599. This patent discloses a control system in which each vehicle has provided to it information regarding the next adjacent downstream occupied or unavailable block; the system relies on distributed (i.e., vehicle carried) data processing or computing. This system avoids the need for multiple communication channels required by the conventional moving block approach. At the same time, however, the single communication channel may provide to any vehicle the identity of the block it occupies, the identity of the next adjacent downstream occupied or unavailable block, and the speed of the vehicle in such block.
With this information, the upstream vehicle's headway can be reduced to approach the headway achievable in moving block systems.
The primary objectives of designing a new railway signaling and traffic control system are to achieve a system which is flexible and capable of optimal passenger throughput. Optimal passenger throughput can be obtained by minimizing vehicle headway and maximizing passenger management. These systems must be compatible with driverless operation and with automatic operation which employs various levels of driver intervention.
It is also a goal that such systems be applicable as an overlay to existing systems to provide various levels of upgraded operation. To achieve this goal, a system must be capable of being applied in a modular fashion to meet the current needs of a particular system operator while being capable of expansion to a higher degree of automatic operation.
Any new system design should also minimize the required wayside hardware, installation and testing time and maximize the system reliability and availability. In addition to redundancy (hot standby) capabilities, high system availability can be achieved by designing a system which has clear fall back operating modes in the presence of failures.
The major obstacles to implementing complete vehicle carried systems are vital methods of having vehicles determine the position of vehicles in front of them and of vehicles vitally controlling switches and routes without vital wayside help. The present invention which uses carborne intelligence in the form of a topographical map database transfers a substantial amount of vehicle control and position of location determination responsibility to the vehicle-based equipment, thereby reducing the information which is required from the wayside-based equipment.
In general, the present invention provides a railway signaling and traffic control system design which centers around the use of communicating vital information between the wayside and the vehicles and the use of an onboard topographic database. With each vehicle containing a vital database which represents the system topology, the system is designed to be very flexible with a minimum of wayside hardware. One major advantage to of this scheme is to concentrate the majority of the equipment with the vehicle, which allows equipment preventive maintenance to be accomplished at a central location. Therefore, the present invention provides the performance advantages of a moving block system, while maintaining a distributed architecture to provide reliable and available service such as that provided in fixed block systems.
The present invention also provides many additional advantages which shall become apparent as described below.